Control of aquatic plant life

ABSTRACT

Submersed and floating aquatic plant life is controlled by contact with an inhibiting amount of a tertiary amine oxide salt of 3,6-endoxohydro-orthophthalic acid, said amine oxide having the structure R&#39;&#39; NOR2R3 where R&#39;&#39; is alkyl having 8 to 20 carbon atoms and R2 and R3 are lower alkyl.

United States Patent [191 Lindaberry Oct. 16, 1973 CONTROL OF AQUATICPLANT LIFE [75] Inventor: Harold L. Lindaberry, Ambler, Pa.

[73] Assignee: Pennwalt Corporation, Philadelphia,

22 Filed: on. 29, 1970 21 Appl. No.: 85,223

[52] U.S. Cl. 7l/66, 71/67 [51] Int. Cl. A0ln 9/20, A0ln 23/00 [58]Field of Search 71/66, 67

[56] References Cited UNITED STATES PATENTS 3,207,593 9/1965 Lindaberry71/66 5/1970 Keckemet 71/66 9/1970 Brian et a]. 71/93 PrimaryExaminer.lames 0. Thomas, Jr. Attorney-Stanley Litz and Carl A. Hechmer,Jr.

[5 7] ABSTRACT 10 Claims, No Drawings CONTROL OF AQUATIC PLANT LIFE Thisinvention relates to the control of plant life in ponds, lakes, andother bodies of water and deals particularly with the use of certainamine oxide salts for chemical control of aquatic weeds and algae.

Numerous chemical agents are known to inhibit, that is, kill or retardthe growth of aquatic plant life, but each agent has disadvantages whichlimit its usage. For example, there are many potent algaecides whichcannot be used because they are extremely toxic to fish at effectiveconcentrations. On the other hand, some agents may effectively controlone species of aquatic plant life and be of little or no value withothers. Still other agents are known which have. limited utility becauseof their high cost (e.g., silver compounds). Thus, there exists the needfor improved means to effectively control the many varieties ofundesirable weeds, fungi, and algae existing in ponds, lakes, streams,etc. without harming fish life.

It is known that the disodium salt of endothal (i.e.,3,o-endoxohexahydrophthalic acid) can be used for aquatic weed control.This compound is quite effective and is relatively non-toxic to fish,but it is somewhat slow in its action, and it is, of course, desirablethat aquatic herbicides act quickly since fast action also aids to avoidloss by chemical degradation as well as diffusion due to water currentsand/or weather conditions. It is also known that tertiary amine salts ofendothal can be used for aquatic weed control (H.L. Lindaberry, U.S.Pat. No. 3,207,593), however, even at relatively low concentration,e.g., on the order of about 0.75 to 2 p.p.m., these salts are toxic tofish.

It has now been discovered, in accordance with this invention, thataquatic plant life, submersed and floating, can be effectivelycontrolled without harm to fish life by application, at low to mediumconcentration, of amine oxide salts (mono-and di) of3,6-endoxohydroorthophthalic acid, wherein said amine oxide salt radicalis derived from an amine oxide which is a tertiary alkyl amine oxidehaving the structure R N RR where R is alkyl having 8 to carbon atomsand R and R are lower alkyl radicals which may be the same or different(e.g., methyl, ethyl, propyl, butyl, etc., i.e., having up to six carbonatoms).

The 3,-endoxohydro-orthophthalic acid salts useful in this inventionwill have less than three double bonds in the endoxocarboxylic acid ringmoiety, but may have i all three degrees of ring saturation andthus willinclude 3,6-endoxodihydroorthophthalic acids,

3,6-endoxotetrahydro-orthophthalic acids,

and 3,6-endoxohexahydro-orthophthalic acids (endothal),

It will be understood that all of the 3,6-endoxohydrophthalic acids andanhydrides may be used to form salts with the tertiary amine oxidesdefined above to give the compounds useful in this invention. Whereanhydrides are used to produce the salts, a mole of water must be addedto cause hydrolysis to the dibasic acid. In addition to theunsubstituted acids, monovalent radical substituted derivatives may beused and such substituents will include halogens (e.g., chlorine,bromine, etc.'), lower alkyl, lower alkoxy, lower aryl, lower aryloxy,nitro, cyano, haloalkyl (e.g., trifluoromethyl and like groups.) Thesubstituted acids from which the salts useful in this invention arederived and their preparation are described in U.S. Pat. No. 2,576,080.

. The preparation of the amine oxide salts of the'3,6-endoxohydrophthalic acids is readily carried out,

without need of critical controls, simply by contacting the desiredamine oxide with a stoichiometric amount of the desired3,6-endoxohydrophthalic acid or anhydride. The temperature for thereaction will usually be between about 30 and C. and the process iscompleted in a short time. As previously stated, both the monoanddi-tertiary amine oxide salts of the acid may be prepared and used inthis invention. To prepare the mono-salt the'stoichiometric amount ofamine oxide used will simply be one-half that required for the dibasicsalt.'

The tertiary amine oxides used to prepare the acid salts used in thisinvention are known compounds, the preparation of which are described inthe chemical lit-' erature. Representative aming oxides embodied by thegeneric formula R .NRR include N,N- dimethyllaurylamine oxide,N,N-diethylmyristylamine oxide, N,N-di-propylstearylamine oxide, and thelike. However, because of availability and cost, mixtures of amineoxides will preferably be used such as the mixtures found inN,N-dimethylcocoamine oxide, N,N- dimethyl soyaamine oxide and the like.Mixtures of the amine oxides may also be used in preparing the activemono or disalts, or two different amine oxides may be used in sequenceto make disalts wherein each carboxyl group of the acid molecule iscombined with a different amine oxide.

Particularly preferred for use in the method of this,

invention are the mono and the disalts of the acid wherein the amineoxide is a'tertiary amine oxide containing two C to C alkyl groups,especially methyl groups, and one higher alkyl group such as octyl,lauryl,

kylamine oxides such as N,N-diethyl-lauryl-amine oxide or fromN,N-dipropyl-higher alkylamine oxide such asN,N-diisopropyloctadecylamine oxide. Salts obtained by reacting endothalwith a mixture of amine oxides, e.g., a disalt obtained by combining onemole.

of endothal with l mole of N,N-dimethyl-cocoamine oxide and l mole oftridecylamine oxide are also effective.

The amine oxide salts of endothal described above act as a contactpoison and for this reason, aquatic weed control is rapidly achievedsimply by treating the area with sufficient material tomaintain a givenstrength of active ingredient in the water surrounding the exposedtissue surface area of the plant, generally from about 0.5 to about 5parts per million parts of the water. For most applications where anentire area such as a pond or lake is treated, the preferredconcentrations of about 1 to 2 p.p.m. of the amine oxide salt will bequite effective as a herbicide with no harm to fish life, althoughconcentrations as high as p.p.m. has generally been observed to be safeto most fish under field conditions. in contrast, the correspondingamine salts of 3,6-endoxohydro-orthophthalic acid are quite v toxic tofish in comparison to the amine oxide salts embodied herein, andconcentrations of the amine salts greater than 0.75 p.p.m. canbe'harmful to fish. As mentioned above, concentrations of the amineoxide salts can be as high as 10 p.p.m. without general harm to fish.However, for control of very resistant weeds, where no fish are present,a dosage of up to about 50 p.p.m. may be employed.

The manner in which the water area may be treated will vary with thespecific problems encountered. Since the active ingredient (amine oxidesalt) is watersoluble, it will diffuse out from the area treated.. intreating small areas where the weed problem is usually critical aroundthe edge of the pond, it is more practical to treat the marginal areafrom the bank than to treat from the center. Furthermore, because of thediffusion of the agents toward the center in static water, control willbe obtained there also. Although aqueous solutions are usually preferredfor economic reasons, solutions of the amine oxide salts in othersolvents may be used for the water treatment. The amine oxide salts arereadily soluble in water, ethanol, isopropanol and other alcohols,benzene, toluene, xylene and other aromatichydrocarbons, diethyl etherand diacetone alcohol. Treatment is desirably accomplished by sprayingon the water or by injection just below the water surface withdistribution as evenly as possible in the area to be treated. Sprayingequipment is'preferably used with solutions of the amine oxide salt. ingeneral, the dilute treating solution will contain about 10 percent toabout percent by weight of active ingredient. It may frequently bedesirable to incorporate a small amount of a dispersant as a mixing aidin the initial concentrate used to prepare diluted treating solutions.For this purpose isopropyl alcohol, diacetone alcohol or other watersoluble alcohols or ketones may be used. Where a dispersant is used, theformulated concentrate will usually contain from about 15 percent topercent of the dispersing agent.

in addition to treating the area with a solution by a sprayingtechnique, the treating agents may also be formulated in a granular formand applied by any of the variety of manual, electrical and gas-poweredwhirling spreaders on the market and which can be adapted for use onboats. This granular formulation consists of an approximately 1 to 10percent (preferably about 5 percent) concentration of active agentdeposited on an inert material such as Attapulgite, Bentonite and otherinert adsorbent granulated clays having a size range of about 8 to 30mesh (U.S. sieve size).

The granular formulations can be simply prepared by spraying the liquidactive ingredient or concentrates thereof into the granular inertcarrier in a rotating or other suitable blender common to the trade forpreparation of pesticide formulations. Although the granulatedformulations can be prepared containing from 1 to 25 percent of activeingredient, it has been found I that 5 percent of the active ingrdientis generally the best concentration to use for obtaining gooddistribution when the formulation is applied. Use of a granularformulation is advantageous for control of submerged algae since thegranular agent sinks to the bottom of the pond.

The amine oxide salts embodied herein have broad spectrum activity andthe invention is effective against practically all aquatic-plants andgrowth which cause problems in lakes, ponds, rivers, streams, etc. Thusthe invention is useful in controlling pondweeds (Potamogeton spp),including bassweed, curly leak pondweed, floating-leaf pondweed, sagopondweed, flatstem pondweed, bushy pondweed (Naias spp), horned pondweed(Zannichellia sp.), coontail (Ceratophyllum sp), water-milfoil(Myriophyllum spp), mud plantain and water-stargrass (Heteranthera spp),bladderwort (Utricularia spp.), burr weed (Sparganium spp), tapegrass,wild celery, eelgrass (Vallisneria sp.), waterweed (Elodea spp.),members of the duckweed family, such as big duckweed (Spirodella sp),duckweed (Lemna spp.), watermeal (Wolffia .spp., Wolffiellasp.)stonewort, muskgrass (Chara spp.) and the filmentous green algaeknown as pond scum (Cladophora, Spirogyra, Pithophora Rhizochlonium,Ulothrix), and the sub-tropical marine algae Gymnodinium brevis whichcauses the red tide disease in fish. in addition, the invention isuseful for the control of slime causing bacteria, such as Aerobacteraerogenes, Bacillus mycoides, Pseidomomonas originosa. In addition toprotecting ponds and lakes, the invention is applicable to the controlof algae and slime forming bacteria in cooling towers and other waterrecirculating systems as used in paper manufacturing processes forexample, in drainage ditches and other water flowing sites.

In the following representative examples presented as illustrative ofthe invention, amounts and proportions of ingredients are given inweight percent and in parts by weight.

EXAMPLE I The herbicidal efficacy of amine oxide salts of endothal(3,6-endoxohexahydro-orthophthalic acid) in controlling aquatic weeds isobserved by a standard method in a series of tests wherein measuredamounts of weed control agent are charged to gallon jars ofdechlorinated tap water containing various species ofrepresentative'aquatic weeds. The samples are maintained at roomtemperature for measured periods of time, and at stated intervals thecontrol of the weeds is reported as the percent of weeds killed relativeto a check sample to which no herbicide is added. The results aretabulated in the following tables:

Test No. 1

Weed Control Agent: Di(N,N-dimethyltridecylamine oxide) salt of endothalAquatic Weed Control of Weed at Concentration of Agent of:

3 p.p.m. 4 ppm.

. after:

4 weeks 6 weeks 4 weeks 6 weeks Elodea 80% 100% 90% 100% Cabomba 60%100% 80% 100% Duckweed 90% 100% 85% 100% Sago Pondweed 100% 100% 87%100% Test No. 2

Weed control agent: Di(N,N-dimethyltridecylamine oxide) salt of endothalControl of Weed at Concentration of Agent of:

Aquatic Weed 1 p.p.m. 2 p.p.m.,

after 4 weeks 6 weeks 4 weeks 6 weeks Elodea 100% 100% Cabomba 95% 100%100% 100%.

Duckweed 100% 100% Coontail 100% 100% 100% 100% Sago Pondweed 67% 50%97% 100% Test No. 3

Weed control agent: Mono(N,N-

dimethyltridecylamine oxide) salt of endothal Aquatic Weed Control ofWeed at Concentration of Agent of:

2.5 p.p.m. 5 p.p.m. 4 weeks 6 weeks 4 weeks 6 weeks Elodea 50% 82% 67%95% Cabomba 94% 100% 94% 100% Duckweed 60% 90% 90% 100% Sago Pondweed65% 95% 30% 62% EXAMPLE II The foregoing results were confirmed in fieldtests involving the treatment of naturally aquatic weeds in a pondlocated in Naperville, Illinois, under summer and fall weatherconditions. The representative aquatic herbicide employed was thedi(N,N- dimethyltridecylamine oxide) salt of endothal at a concentrationof 2 p.p.m. The tests were made in 2-foot diameter, 2 foot deep, plasticenclosures set in the pond, with the following results.

Aquatic weed kill after 14 days Duckweecl 95- Chara I Elodea 100Pondweed (Potamogeton pusillus) 100 In the control enclosure to which noherbicidal agent was added, the weeds continued to thrive.

EXAMPLE Ill Tests were carried out as described in Example I using otherrepresentative amine oxide salts embodied in this invention.

Test No. 1

Weed control agent: Mono(N,N-bis(2-hydroxyethyl) cocoamine oxide) saltof endothal.

Aquatic weed Control of weed at Concentration of Agent of 2 p.p.m. 4weeks 6 weeks Coontail 100% 100% Sago Pondweed 25% 50% Elodea 25% TestNo. 2

Weed control agent: Mono(N,N-dimethylcocoamine oxide) salt of endothalAquatic weed Control of weed at Concentration of Agent of 1.5 p.p.m. 4weeks 6 weeks Coontail 100% Sago Pondweed 77% 100% Elodea 35% 45%Example IV Conventional fish toxicity tests were conducted todemonstrate the tolerance of fish to the amine oxide salts embodied inthe present invention, and the relatively high fish toxicity ofrepresentative analogous amine salts. In the tests, three goldfish areplaced in each of a series of gallon jars containing dechlorina tedwater 24 hours later a measured amount of the aquatic herbicide is addedand after 72 hours has passed, the effect on the fish is recorded. Theresults are reported in the following table.

The foregoing results illustrate that the amine oxide salts aresurprisingly relatively harmless to fish compared to amine salts, asignificant advantage for the present invention.

EXAMPLE V .The dimethylcocoamine oxide salt of endothal is applied ataconcentration of 4 ppm to aquaria containing the aquatic-weeds Nitellaand potamogeton crispus.-

One week after treatment, the weeds slumped to the bottom and started todecompose. After three more weeks had passed, it was observed that theweeds in the treated aquaria had completely decomposed, whereas weeds inuntreated control aquaria remained in a healthy growing condition.

EXAMPLE v! A small fish pond inAmbler, Pennsylvania containing largequantities of filamentous green algae, was treated in early autumn with3 ppm. of the dimethylcocoamine oxide salt of endothal. Within 10 daysthe green algae had disappeared from the pond and none was seen toreturn when observed four weeks from the date of application of theherbicide. None of the abundant fish life in the pond was killed norappeared to be harmed in any way by the algaecide treatment.

I claim:

1. A process to inhibit aquatic plant life which comprises contactingsaid plant life with an inhibiting amount of a tertiary amine oxide saltof 3,6-endoxohydroorthophthalic acid, said tertiary amine oxide havingthe structure R NR R where R is alkyl having 8 to 20 carbon atoms and Rand R are lower alkyl.

2. A process in accordance with claim 1 wherein the salt is thedi-dimethyltridecylamine oxide salt of the acid.

3. A process in accordance with claim 1 wherein the salt is themono-dimethyltridecylamine oxide salt of the acid.

4. A process according to claim 1 wherein the salt is themonodimethylcocoamine oxide salt of the acid.

5. A process according to claim 1 wherein the salt is thedidimethylcocoamine oxide salt of the acid.

6. A process according to claim 1 wherein the salt is thedidimethyl-(hydrogenated)tallowamine oxide salt of the acid.

7. A process according to claim 1 wherein the salt is thedi-dimethylhexadecylamine oxide salt of the acid.

8. A process according to claim 1 wherein the salt is themono-dimethylhexadecylamine oxide salt of the acid.

9. A process according to claim 1 wherein the concentration of the amineoxide salt is within the range of about 0.5 part to 10 parts per millionparts of water surrounding the plant life. 7

10. A process according to claim 1 wherein the concentration of theamine oxide salt is from about I to 7 about 2 parts per million parts ofwater surrounding the plant life.

CERT? 3K5 Patent No. 3,765,863 Qet ls "1973.

Iavenwfla) Har ld-L. Lindaberry I 1%; is certified thaw warm: upg aea'fain we eirove i deutified pateizt and that wid m'izwm Pawn; am here??come: ac chm below:

Line 4 of the abetract, "R' NR R shouldread' R' NR R Column 2, line 38,formula 3' NR R shou'ld read R NR R Co lurfi n 5, line 38 insert"occurring" after haturally and before Column 6, Example iv, line 27"D(N,'N-dimethYltridecYc-flmine oxide) should read Di(N,N-dimethyltridecyalmine oxide)*-- 7 Column line "3 p. p. m; shouldppearunder the heading "Concentration" q a Column 7,; Claim 1, Line 9,correct the chemical formu lato rec'd R'RR R Y Signed and sealed this19th day of February 1974.

(SEAL) Attestz' I EDWARD M,FLETCHER,JR c. MARSHALL DANN AttestingOfficer Commissioner of Pat'e nt s Ugcomoc new, us. Iqaluit mum on: no.o-lu-n'u' FORM PC4050 (O-0N

2. A process in accordance with claim 1 wherein the salt is thedi-dimethyltridecylamine oxide salt of the acid.
 3. A process inaccordance with claim 1 wherein the salt is themono-dimethyltridecylamine oxide salt of the acid.
 4. A processaccording to claim 1 wherein the salt is the monodimethylcocoamine oxidesalt of the acid.
 5. A process according to claim 1 wherein the salt isthe didimethylcocoamine oxide salt of the acid.
 6. A process accordingto claim 1 wherein the salt is the didimethyl-(hydrogenated)tallowamineoxide salt of the acid.
 7. A process according to claim 1 wherein thesalt is the di-dimethylhexadecylamine oxide salt of the acid.
 8. Aprocess according to claim 1 wherein the salt is themono-dimethylhexadecylamine oxide salt of the acid.
 9. A processaccording to claim 1 wherein the concentration of the amine oxide saltis within the range of about 0.5 part to 10 parts per million parts ofwater surrounding the plant life.
 10. A process according to claim 1wherein the concentration of the amine oxide salt is from about 1 toabout 2 parts per million parts of water surrounding the plant life.